Hi all
Only had this truck 5 months, 7.3 idi, it ran fine when i bought it even though the fuel filter was leaking, repaced that and all was well until a few weeks later when I was on the motorway (UK) doing around 75mph when the fuel filter light came on, within minutes the truck was loosing power so i pulled off onto quieter roads, within another mile the motor cut out, I had a new filter behind the seat so i filled it with diesel and fitted it, got the air bled out and set off again,drove 2 mins to a petrol station and filled the rear tank with Diesel then switched to that just in case the fuel in the front tank was contaminated, Truck ran fine for next 5 mins or so until the filter light came on again, the motor was surging and running rough I managed to limp to the Girlfriends house where the truck cut out and will not start again, I had it transported home, I checked the fuel pressure at the schrader valve and it was 3psi so i bought a 7 psi electric pump, fitted it up front I know near the tank is better) checked the fuel pressure again and now at the schrader valve i get 2.5 psi with just the pump running and 0.5psi with the motor running??? So I took the fuel line to the IP off and checked the pressure there and it's just over 4psi, I can blow through the filter by mouth (yum yum) and there is no blockage, blew down the fuel line into tank with compressed air and still the same fuel pressure, left it like that a week and now I appear to be getting air in the fuel system somewhere pfft, the reason i bought a ford was because of all the trouble i've had with Chevy trucks, not impressed any ideas folks?

 

I'm none too sure on how much fuel should be coming out of that valve but it does sound low, could this be a failing lift pump?

 

I was told on this site that the fuel pressure should be between 4 and 5psi at the schrader valve, it was 3psi with the factory pump and 2.5psi with the new electric pump, think we can rule out both fuel pumps

 

Check your engine oil, make sure your not pumping diesel into your crank case. Replace your mechanical pump and toss the electric one in the can. Make sure you have all your fuel line connections tight.

 

Did you by pass the mechanical pump when you installed the electric one? If the original mechanical one is still hooked up with the electric one, it is not a good idea to run it this way. Check the fuel lines, especially where they exit the fuel tanks for rusted threw spots.

 

It cant be pumping fuel into the sump because i bypassed the mechanical pump, you seen the price of car parts in the UK? hence electric pump, Lines are tight i just did them

 

If you haven't already bypassed the water seperator, Do it. That sounds like it might be SOME of the problems, not all. The new design lift pumps are designed differently aswell, OEM had a bend to it, The replacement is straight. Doing the lift pump sucks, I'll tell you that one haha its just in the sweet spot where getting good access from the top or bottom is uncomfortable at the least.

 

The water seperator is part of the fuel filter or is there another? i'm using fuel filters with built in water seperators as they are cheaper and don't leak. Just checked the fuel lines and they are like new, no rust at all and still have labels on them

 

The 7.3 engines use the water seperater built in the filter like you are using. The earlier modle trucks that had a 6.9 engine had a seperate water seperator mounted on the firewall that was prone to leak air into the fuel system.
I sounds like you have a fuel restriction some where. Take a length of fuel hose and place it on the suction side of the electric pump. Place the other end in a container of fuel. Run the pump and check for fuel pressure, if you have good pressur set up this way, you have a restriction or air leak before the pump.

 

Finally got time to get back on the truck yesterday, I found an old Holley red electric fuel pump i'd forgotten I had, stripped it down n cleaned it out, man are they cheap inside. Anyway I replaced the short rubber pipe between the hard line and the pump, put the Holley pump on and she runs better than it has ever in the time i've owned the truck it even kicks down when i floor it now Today the wipers stopped, over worked in the UK i guess lol, turns out the magnet have come unglued and jammed the motor pffft

 

Glad you got things sorted out, and she's running again!

 

Good to hear, jsut so you know for future reference:

PSI at filter is NOT 4-5 psi....this is too low. It needs to be 7psi. For a test of volume, you need about a 1/3 of a pint in 10 seconds of cranking.

 

1993 Ford IDI 7.3L; I am able to drive the truck ONE mile and it sputters and dies. Today I got it started and timed it in the driveway and it ran a total of 7 minutes and seemed to run out of fuel and died. Even when running I was getting NO fuel out of the Schrader valve at the filter mount. I was also getting no fuel out at the injectors but had fuel at the connection from the lift pump and out of the filter to the injector pump but I have not measured any pressures, Now I read that the lift pump should produce 1/3 cup in 10 seconds cranking. I will try that tomorrow. I had good flow out of the lift pump to filter line today but I do not know about the pressure nor the volume it was putting out. I had just had a Reman injector pump put on and drove it maybe 20 miles to take the core item back to the parts house. I have blown air backward through the fuel lines, looked for leaks, etc but I am not gaining on this issue. Each time it died one mile from home I could wait about an hour and it would start and run nearly all the way home again.Can anyone give me more ideas as to finding this problem.

 

75 Dually,
My 1993 7.3L, IDI had exactly the same leaking problem with the water separator at the bottom of the filter. I have solved that by using a 33417 WIX filter.

 

Just had this problem. Figured out a hose clamp was missing and the rubber line going to the fuel pump. It disintegrated from all the salt. Half of it was gone. It caused the engine to ingest a ton of air. Fuel filter light would come on, truck would miss, lose power, or just die a few times. Put a new hose clamp on and everything seems to be good so far.